Mathematica: Webel: A concise i:/o: notation is often used for indicating input/output cells in Mathematica notebooks in Webel's online help pages and tutorials, instead of 'In[n]:=' and 'Out[n]='. (Also learn how to hide them completely in notebooks.)
Mathematica: TIP: Notebooks: Automatic Cell Grouping driving you up the wall? Try Manual Grouping and make it part of your workflow!
Webel: SysML4Mathematica: POLICY: Handle flow sign changes via a single negative (not duplicated and "adjusted" algebra). This strategy may come at a very slight performance cost (for benefit of more robustness).
Webel: SysML4Mathematica: TIP: Representing Mathematica Paclets and their inter-dependencies as SysML Packages modelled in SysML Package Diagrams can really help you organise your Wolfram Language code on complex projects!
Webel: SysML4Mathematica: TIP: Representing Mathematica functions as SysML ConstraintBlocks modelled in Block Definition Diagram (BDD) overviews can really help you organise and document your Wolfram Language code on complex projects!
Webel: SysML4Mathematica: TIP: Representing Mathematica functions as SysML ConstraintBlocks modelled in SysML Parametric Diagrams and as Activities in SysML Activity Diagrams is super for analysing the dependencies between functions and their arguments!
Mathematica: Notebooks: Automatic Cell Grouping mode can be a "royal pain", turn it off by setting Cell > Grouping > Manual Grouping
The integration between Wolfram Workbench and Mathematica is partly gammy (as of latest versions 2022-08-23)